In magnetic tape devices with rotating headwheels, it is particularly necessary to have noise-free transmission of signals to the headwheel and from the headwheel to stationary portions of the device. After initial attempts using slip-rings, it was found that rotating magnetic transducers provided satisfactory performance. However, newer devices, for recording of digital video signals, have such large data streams that transmission by means of magnetic transducers runs into difficulties.
It is known to use optical devices for transmission of signals between the headwheel of a videotape device and its stationary portion. These devices, however, operate with an axially aligned light beam, which necessitates elaborate multiplexing systems if simultaneous transmission of multiple signal channels is required.